A non-contiguous polymer deposit can form on the plasma-exposed surface, e.g., the bottom surface of a silicon upper electrode, during a main etching step for etching a dielectric material on a semiconductor substrate, such as silicon oxide or a low-k dielectric material layer.
Process window etch rate and etch uniformity can be restored to acceptable levels by cleaning the silicon surfaces of electrode assemblies.
The cleaning solution to be applied to the silicon surface of the electrode assembly comprise various reactive chemicals, for example, acids, such as hydrofluoric acid, to dissolve impurities. In particular, commonly owned U.S. Patent Application Publication Nos. 2006/0138081 A1, 2006/0141787 A1, and 2006/0141802 A1, which are incorporated herein by reference in their entirety, disclose acidic cleaning solutions for cleaning the silicon surfaces of electrode assemblies.